The main thrust of this is the study of the long term (10 years or more) control of food intake in the rhesus monkey (Macaca mulatta). In the course of this work we have discovered that monkeys which develop obesity during middle age show a high incidence of spontaneous diabetes mellitus. Longitudinal studies are being made to discover the nature of the very early stages of the development of the disease. Indications are that the earliest sign is the development of hyperinsulinemia in the absence of hyperlipidemia or hyperglycemia. In conjunction with the above work we are investigating the effects of social interaction stress on the development of abnormal carbohydrate and lipid metabolism. In addition, we continue our studies on the role of the CNS on feeding behavior and carbohydrate and lipid metabolism.